Blue Crab Anatomy
(Male)

Male Abdomen
Ventral View

Males have only two pairs of pleopods and they are located anteriorly on the abdomen, on segments 1 and 2. Both function in the transfer of sperm to the female during copulation. The long, curved, tubular first pleopod is the gonopod. It, not the penis, is the interomittent organ used to deliver spermatophores to the female gonopore. The second pleopod is much shorter and functions as a piston to push spermatophores through the hollow core of the gonopod.

See the Natural History Museum of Los Angeles County Crustacea Glossary for a detailed definition of terms.